1. Field of the Invention
The present invention generally relates to a support structure. More particularly, the present invention relates to the mainframe to support a process cell.
2. Background of the Related Art
Electroplating, previously limited in integrated circuit design to the fabrication of lines on circuit boards, is now used to deposit metal films, such-as copper, on substrates to form interconnect features, e.g. vias, trenches, or contacts. One feature filling embodiment that utilizes electroplating requires initially depositing a diffusion barrier layer on the substrate by a process such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). A seed layer is deposited on the substrate by PVD or CVD to define a plating surface. A metal film is then deposited by electroplating on the seed layer. The seed layer is typically formed from the same metal as the subsequently electroplated metal film, so the seed layer becomes contiguous with the metal film. Finally, the deposited metal film can be planarized by another process, e.g., chemical mechanical polishing (CMP), to define a conductive interconnect feature. Electroplating is performed by establishing a voltage/current level between the seed layer on the substrate and a separate anode to deposit metal ions on the seed layer.
Such PVD, CVD, electroplating, CMP, or other operations associated with semiconductor processing require a stable platform. In electroplating, for example, any vibration/motion that is transferred to an electrolyte cell can be transferred to the electrolyte solution contained within the electrolyte cell. Such vibration/motion of the electrolyte solution within the electrolyte cell can effect the uniformity of the metal film that is deposited on the seed layer during electroplating. Other processes such as CVD or PVD are also adversely effected by vibration and/or motion of the cell of the processing chamber carrying out the particular process during processing.
Robots are often used in conjunction with processing systems such as those that perform electroplating, PVD, CVD, or CMP operations. The robots are accurately aligned with the process cells to effect transfer of the substrate from a robot blade in which the robot blade supports the substrate, to the process cell, or a substrate holder system associated with the cell. Modern systems are designed so multiple substrate can be processed in identical, though different, process cells simultaneously to increase processing throughput. The robots are therefore often required to simultaneously transfer multiple substrates between multiple sets of cells. To provide for such simultaneous transfer of multiple substrates between multiple sets of process cells, all of the robots are correctly aligned with the appropriate sets of process cells. Such alignment is compromised by any vibration/displacement that occurs between the robot and the process cell, or the substrate holder system associated with the process cell.
Therefore, there remains a need for a stable cell platform to support process cells, metrology cells, SRD cells, etc. The stable platform should preferably limit displacement/vibration between the platform and the cell.